USGS Volcano Hazards Program Volcano Update

Activity Summary: Eruption at two locations continued with no significant changes. The summit tiltmeter network recorded slowed DI inflation and the lava-lake level rose. At the middle east rift zone, the Pu`u `O`o vent continued to feed the Kahauale`a 2 lava flow that was active as small scattered breakouts burning forest to the northeast. Gas emissions remained elevated.

Recent Observations at Kilauea summit: The summit tiltmeters recorded slowing DI inflation and the lava-lake level rose to an estimated 55 m (180 ft) below the floor of Halema`uma`u Crater by this morning. Gas emissions continued to be elevated. Although not measured this morning, a very small amount of ash-sized tephra (mostly fresh spatter bits and Pele's hair from the spattering sinks) was likely carried out of the vent with the gas and deposited onto nearby surfaces.

The summit remained inflated. Seismic tremor levels were low and variable including 2 dropouts overnight. Eleven earthquakes were strong enough to be located beneath Kilauea Volcano in the past 24 hours: 1 in the Ka`oiki Pali area, 4 within and beneath the upper east rift zone, and 6 scattered on south flank faults. GPS receivers spanning the summit caldera recorded line length changes that mimicked the short-term trends in tilt (DI tilt events) over the past month; the long-term, cross-caldera measurements indicate continued extension at a rate averaging 10 cm/yr (4 in/yr) since March, 2010.

Background: The summit lava lake is within a nearly-cylindrical vent cavity with a diameter of ~160 m (520 ft) and nearly vertical sides inset within the east wall and floor of Halema`uma`u Crater. Its level has varied from about 25 m to more than 200 m (out of sight) below the floor of Halema`uma`u Crater. The vent has been mostly active since opening with a small explosive event on March 19, 2008. The surface level of the lava lake has remained mostly below the inner ledge (~31 m or 100 ft below the floor of Halema`uma`u Crater on October 29, 2012) and has risen above and flooded the ledge in October 2012 and January 2013 before receding to greater depths. The lake level responds to summit tilt changes with the lake generally receding during deflation and rising during inflation.

Recent Observations at the middle east rift zone vents: The tiltmeter at Pu`u `O`o cone recorded fluctuations over a weak increase that mimicked the summit DI tilt. Gas emissions remained elevated with rates ranging between 150 and 450 t/d since July 2012; the measurements are made at a greater distance from the sources (than the summit measurements) where the plume is more easily characterized. GPS receivers on the north rim and south flank of Pu`u `O`o cone recorded minor fluctuations over weak extension (about 1 cm over the past 3 months).

No changes at Pu`u `O`o: Spatter cones on the floor of Pu`u `O`o crater continued to display persistent glow. The northeast spatter cone continued to feed the Kahauale`a 2 lava flow, which extended 7.3 km (4.5 mi) to the north; however, the flow is most active about 5 km (3.1 mi) northeast of Pu`u `O`o (per 12/06 mapping) and advanced only 280 m (920 ft) northward between 11/27 and 12/06. When weather allows, views from the PNcam and R3cam (working intermittently) showed continued lava activity in the distance as multiple, small scattered breakouts well behind the tip of the northeastern-most branch of the Kahauale`a 2 flow (see map) and several spots of burning forest.

Background: The eruption in Kilauea's middle east rift zone started with a fissure eruption on January 3, 1983, and continued with few interruptions at Pu`u `O`o Cone, or temporarily from vents within a few kilometers to the east or west. A fissure eruption on the upper east flank of Pu`u `O`o Cone on Sept. 21, 2011, drained the lava lakes and fed a lava flow (Peace Day flow) that advanced southeast through the abandoned Royal Gardens subdivision to the ocean within Hawai`i Volcanoes National Park in early December 2011. The flows stalled and re-entered the ocean starting on November 24, 2012 until activity started to decline and the ocean entry ceased in August 20, 2013; the flow was dead by early November, 2013. The Kahauale`a flow, which started from the spatter cone/lava lake at the northeast edge of the Pu`u `O`o crater floor in mid-January, 2013, was dead by late April, but a new flow (informally called Kahauale`a 2) became active in the same general area in early May. In general, activity waxes with inflation and wanes with deflation.

Hazard Summary:East rift vents and flow field - near-vent areas could erupt or collapse without warning with spatter and/or ash being wafted within the gas plume; potentially-lethal concentrations of sulfur dioxide gas may be present within 1 km downwind of vent areas. Active lava flows within forest can produce methane blasts that propel rocks and other debris into the air. All recently active lava flows are within Hawai`i Volcanoes National Park and adjacent State land managed by the Department of Land and Natural Resources or the Office of Hawaiian Affairs; the lava flows do not pose an imminent hazard to any structures not already within the County-declared mandatory evacuation zone. Kilauea Crater - ash and Pele's hair can be carried several kilometers downwind; potentially-lethal concentrations of sulfur dioxide can be present within 1 km downwind.

Viewing Summary:East rift zone flow field - Most of the flow field is within the closed-access Kahauale'a Natural Area Reserve (NAR) or the Wao Kele o Puna Forest Reserve (DLNR, OHA) and can only be viewed from the air. Under favorable weather conditions at night, distant glow from the active flows can be seen from the County Viewing Area at Kalapana (Lava hotline 961-8093) and from the end of the Chain of Craters Road within Hawai`i Volcanoes National Park. Pu`u `O`o Cone and Kilauea Crater - these areas are within Hawai`i Volcanoes National Park; Park access and viewing information can be found at http://www.nps.gov/havo/planyourvisit/lava2.htm.